Control system for domestic oil burners



April 9, 1929.

Filed April 6, 1925 I'A/MGA/TOEJ- Luv/.5 L. Scarf:

Patented Apr. 9, 1929.

UNITED STATES 1,708,706 PATENT OFFICE.

LEWIS L. SCOTT, OF ST. LOUIS, MISSOURI, ASSIGNOR TO ELECTROL, INC. OF MISSOURI,

OF ST. LOUIS, MISSOURI, A CORPORATION OF MISSOURI.

I CONTROL SYSTEM FOR DOMESTIC OIL BURNERS.

Application filed A r l s, 1925. serial No. 20,985.

This invention relates to an automaticcontrol system for oil burners. One of the objects is to provide a transformer which 15 connected up to the ordinary 110 volt alternating current line through anautomatic switch, which switch is used for controlling a fuel projecting means. The secondary side of the transformer is wound to produce a voltage of around 10000 to 15000 volts, and said 1 secondary winding connects directly to an electric ignition device. By this arrangement, I avoid the use of a vibrating spark COll V such as shown in my prior Patent No. 1,427

' i 700. The transformer I employ is of small capacity, so that the high voltage circuit is not dangerous.

A further object of this invention is to automatically control the transformer by a room thermostat, which thermostat also controls the operation of the fuel projecting means.

A further object is to provide a room thermostat that will start the fuel projecting means on the closing of a contact of said thermostat at a predetermined room temperature, and will stop the fuel projecting means on the opening of the contact of said room thermostat at a predetermined higher room temperature, said thermostat being so ar-' ranged as to take care of this differential in temperature. i

In the drawing, the figure 1s a diagrammat-ic outline of my automatic control system.

The numeral 1 indicates an electric motor, which operates a blower wheel 2 contained in a housing 3, and also a fuel pump 4. The numeral 5 indicates a suction pipe from the pump 4, which is adapted to be connected to a fuel tank (not shown). The numeral 6 indicates a discharge pipe from the pump 4 which connects to a s ray nozzle 7. Air from the blower wheel 2 1s conducted around the spray nozzle and mixed with the fuel to support combustion. The numeral 8 indicates a s ark plug which is used for igniting the fuel One of the terminals of said spark plug is grounded and the other is connected through the wire 9 to the secondary coil 10 of the transformer 11. This secondary coil is of high enough voltage to cause a substantial spark to jump across the terminals of the spark plug 8. The primary winding of the transformer 11 is connected to the main power wires 12, which usually carry a current of 110 volts, through wires 13 and 14, and

, and which has terminals 20 mounted at one end of the same, which terminals are adapted to be electrically connected to complete the circuit over wires 16 and 18, through the medium of the switch connections 21, when the mercury in said tube is run to the righthand side of said tube, due to a tilting action which will be later described. Said tube19 is mounted on a clip 22, which clip is secured to a post 23. This post is pivoted at 24 and is provided with an adjustable stop 25 to limit its tilting movement to the left. An arm 26 is attached to the post 23 and has mounted on it an adjusable weight 27. The numeral 28 indicates a bar of iron secured to the clip 22 and post 23, and isadapted to be acted on by an electro-magnet29. The numeral 30 indicates a transformer, the primary side 31 of which is connected to the main power wires 12,'and the secondary side 32 of which is of low Voltage, usually about fifteen to eighteen volts. A wire 33 runs from the secondary side of the transformer 30 through the coil 34 of the magnet 29, through a safety switch 35 (which switch is clearly described in my pending application Serial No. 717,190, filed May 31st, 1924, and which forms no part of this invention), through awire 36, through a coil 37 of a magnet 38, to a contact screw 39,

through contact 40 on a room thermostat 41,

and from said room thermostat through a wire'42 back to the secondary side 32 of the transformer.

I will now describe the action of the room thermostat. Normally, the contact screw 39,

which is supported by a leaf-spring 43, is iu-a position to the left of that shown on the drawing, and this spring is resting against a stop pin 44. The numeral 45 indicates a piece of soft iron which is secured to the spring48. When theroom temperature lowers, the room thermostat contact 40 will move to the left until contact is made with the screw 39, whereupon current will flow throughthe magnet 38 and will attract the small armature 45, so as to move contacts 39 and 40 a small distance to the right; this action will cause an increase of pressure between the last named contacts. Upon the closure of contacts 39 and 40, current will be sent through the magnet 29, which magnet will attract the armature 28, and the mercury tube 19 will be moved, so as to run the mer cury to the righthand side and close the contacts in said tube so that current will be sent to the electric motor 1 and to the transformer 11. Said motor will operate the pump 4, causing a fuel spray at the nozzle 7 and the blower wheel 2 causing a flow of air around the nozzle 7. The tilting of the tube 19 will also bring the transformer 11 into action, which will cause a spark at the terminals of the spark plug 8 for the purpose of igniting fuel. After the burner has been operating for a period of time, the room temperature in whlch thermostat 41 is located, will be raised until the contact 40 will move away from the contact'89, and will permit the tube 19 to be tilted to the left, as shown in the drawing, because of the fact that the mag net 29 is (lo-energized, and the weight 27 will cause tube 19 to move to the position shown. The magnet 38 will likewise be de-eriergized, and the spring 43 will cause the contact 39 to move away from contact 40. It-will be obvious that, due to this action, the contacts 39-and 40 will be closed at a difl'erent,or lower, room temperature than when these contacts are broken. Also, that due to the flexing of the thermostat 41 and the movement of the contacts 39 and i0 to the right when the magnet 38 is energized, a higher room temperature will be required to break these contacts than obtained when the contact was made. The arrangement thus provides a time-regulatcd circuit control for the system, as the element of time is involved in the fall of the temperature the given number of degrees necessary to make contact, and likewise in the rise of temperature a suflicient number of degrees to break the contact.

An adjusting screw 38 forms a part of the core of the magnet 38, and by adjusting this screw the extent of movement of contacts 39 and 40 under the influence of the magnet 38 may be regulated.

On oil burner control systems of the past, such as is shown on my Patent No. 1,427,700, it has been customary to use what is known as the three-wire room thermostat, which makes an electric contact to start the burner, and also makes an electric contact to stop the burner. If the electric contact which is made at the room thermostat to stop the burner should be dirty, then the burner would not,

stop, and this might lead to serious consequences. With the arrangemcntshown in the present invention, the burneris adapted to be started upon the making of a contact and stopped upon the breaking of a contact at the room thermostat, and, therefore, there could be no serious consequences due to the fact that thecontacts of the room thermostat were dirty. The expression single-conflict room thermostat, in ccrtain'of the claims, is intended to refer to a thermostat operating as last described, as distinguished from the three-wire room thermostat previously referred to. i

It will also be seen that I have provided a system of ignition which is extremely simple and effective, and which is automatically controlled by the room thermostat.

I claim: I

1. In the art of controlling the operation of oil burners, an automatic control switch, a single-contact room thermostat for electrically controlling said automatic switch and operating, in its contact position, to cause said switch to function to start the burner and in its open position, to permit the switch to function to stop'the burner, and an electric device for varying the elfective contact position of the thermostat and operating to permit the closing of the contacts thereof at a predetermined room temperature and the opening of said contacts only at a higher temperature.

2. In the art of controlling the operation of oil burners, an automatic control switch, a single-contact room thermostat for electrically controlling said automatic switch and operating, in its contact position, to cause said switch to function to start the burner and in its open posit-ion, to permitthe switch to function to stop the burner, and a magnet co-operating therewith for varying the elfective contact position of the thermostat and operating to permit the closing of the contacts thereof at a predetermined room temperature and the opening of said contacts only at a higher temperature.

3. In the'art of controlling the operation of oil burners, a single-contact room thermostat for electrically controlling the operation of the burner and operating in its contact position to start the burner and in its open position to stop it, and electrically operated diiferential contact mechanism for said thermostat whereby said burner will be started by the closing of the contacts of the no room thermostat at a predetermined room temperature and will be stopped by the opening of said contacts only at a predetermined higher room temperature. 7

4. In the art of controlling the operation of oil burners, a single-contact room thermostat for electrically controlling the operation of the burner and operating, in its contact position, to cause the burner to start and in its open position to stop the burner, and 120 tion of the burner and operating, in its contact position, to cause the burner to start and in its open position, to stop the burner, magnet-operated difierential contact mechanism for the thermostat whereby the burner will be started 'by the closing of the contacts of the thermostat at a predetermined room temperature and will be stopped by the openin of said contacts only at a predetermined higher room temperature, and adjustable means to limit the variations in the contact positions of the thermostat.

6. In the art of controlling the operation of oil burners, an automatic control switch, a

room thermostat for electrically controlling said automatic switch and operating, in its contact position, to cause said switch to function to start the burner and in its open position, 'to permit the switch to function to stop the burner, an electric actuating device energized in the contact position of the thermostat, and a movable member for controlli'n the circuit of said thermostat and 1 overne in position by the condition of sai electric actuating device, said member by its change in position controlled by said electric actuattion to permit the switch to function to stop the burner, an electric actuating device energized in the contact position of the thermostat, and means for controlling the range of temperature required to break the contact said contact when broken, comprising a contact member controlling the circuit of the thermostat movable to one position by said electrical actuatin device when it is-energized and automatically movable to a difierent position when said electric actuatin device is de-energized by the breaking o the contact of theroom thermostat.

8. Inthe art of controlling the operation of oil burners, an automatic control switch, a room thermostat for electrically controlling said automatic switch and operating, in its contact position, to cause said switch to function to start the burner and in its open position, to permit the switch to function to stop the burner, an electric actuatin device energized in the contact positionoftlie thermostat, and means for causing said thermostatto function either to make or break its contact only after a change in temperature affecting the same of a given number of degrees, com rising a circuit-controlling member movab e by said electric actuating device when it is energized and operating to increase to a predetermined degree the range of movement. of said thermostat under variations in temperature from out-of-contact to contact position and from contact to out-of-contact position.

In testimony whereof, I have hereunto set my hand.

LEWIS 1:... SCOTT.

g of the thermostat when made or to establish 

